Mass spectrometry (MS) will be utilized to develop automated methods for quantitative analysis and structure determination applicable to 10 to the minus 6th power to less than 10 to the minus 12th power g samples of biomedical importance. Methods include structure determination of complex molecules utilizing collisional activation (CA) mass spectra to determine fragment structures corresponding to individual spectral peaks, and MS/MS in which complex mixtures from biological samples are analyzed by component ionization and MS separation followed by CA identification of the separated ion species. A tandem double-focusing instrument will be applied to such studies for large biological molecules. An on-line computer system will be completed for data acquisition and feedback control for this instrument. Submicrosecond droplet vaporization will be developed as a method to obtain MS information from nonvolatile biological molecules. CA mass spectra and other techniques will be used to extend our knowledge of unimolecular ion decomposition mechanisms.